Abstract
Studying the California Independent System Operator (CAISO) day-ahead and real-time markets for the period January 2015 to December 2017, we characterize the growth of curtailment and negative-priced power from renewable generators. Results show that renewable curtailment is growing rapidly, tripling to over 400 GWh from 2015-2018. Negative-priced renewable power is larger and also growing rapidly, reaching 1.5 TWh in 2017 for 40% CAGR.Resource-hours for negative pricing grew nearly 3-fold from 80,006 to 217,728 hours, with the highest single generator reaching 955 hours in 2017 or 33% of the daylight solar hours. Spatially, the quantity of negative-priced power is concentrated at a few dozen renewable generators, reaching peaks of 170GWh at the largest generator. We also consider an averaged-price model (NetPrice) that smooths over fluctuations to estimate the usable quantities of low-priced power. Results for NetPrice show a much larger quantity of low-priced power available than with either negative-pricing or curtailment alone. Overall, these results suggest both that opportunity power is a substantial and growing resource and a number of opportunities to exploit it.
Highlights
Aggressive Renewable Portfolio Standards (RPS), and resulting rapid growth of variable renewable generation in power grids around the world aim to reduce the carbon-emissions and other negative environmental impacts of fossil-fuels
This study analyzes opportunity power in the California Independent System Operator (CAISO) for the period January 2015 to December 2017 with the objective of characterizing the growth of curtailment and negative-priced generation to create insights that can inform strategies to both reduce their occurrence and to exploit the opportunity that this power provides for some productive use (Note 2)
Because of the large quantities of solar power in CAISO, the occurrence of opportunity power is heavily concentrated in those daylight hours, as well as in certain seasons
Summary
Aggressive Renewable Portfolio Standards (RPS), and resulting rapid growth of variable renewable generation in power grids around the world aim to reduce the carbon-emissions and other negative environmental impacts of fossil-fuels. Economic dispatch has successfully reduced curtailment, providing economic incentives (payments) and disincentives (negative payments) for generation Renewables are increasing their participation in markets by bidding their opportunity costs, increasing the ability to manage and optimize supply and demand recognizing transmission constraints. This study analyzes opportunity power in the California Independent System Operator (CAISO) for the period January 2015 to December 2017 with the objective of characterizing the growth of curtailment and negative-priced generation to create insights that can inform strategies to both reduce their occurrence and to exploit the opportunity that this power provides for some productive use (Note 2). We characterize negative pricing in the day-head and real-time markets and include CAISO’s reported curtailment for renewable generation (initiated in 2016). We use this information to estimate negative-priced generation. While curtailment is a smaller quantity, it continues to increase rapidly, tripling to over 400
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